Classification of Seizures and the Epilepsies

Epilepsy classification provides a framework for diagnosis. While the primary goal of classification is to improve clinical epilepsy care, accurate classification is also important for epidemiologic reasons. Classification based on seizure and epilepsy type allows one to identify the most likely type(s) of etiology or syndrome and target investigations to these areas. The International League Against Epilepsy revised the Classification of the Epilepsies in 2017. This framework allows diagnosis of epilepsy at three levels, depending on information and resources available, and also addresses the broad concepts of etiology and associated comorbidities at all levels. They are level 1: seizure types, level 2: epilepsy based on seizure type, and level 3: epilepsy syndrome. Etiology of epilepsy must be considered at all levels of diagnosis. Though patients may share a unifying etiological diagnosis, phenotypic variability may still be marked, likely reflecting modifier genes and/or environmental factors.